Sulfate sulfite oxidation

In spite of its wide application, the mechanisms of this reaction remain obscure. Many diverse arguments have been published since the reaction was first investigated in 1897 (Bl, C5, C9, F7, J6, M5, P9, R2, S5, W2, W4, Yl, Y4). Cooper et al. (C9) introduced this method as a yardstick for the measurement of volumetric mass-transfer coefficients in gas-liquid contacting. Karow et al. (Kl) later concluded that the sulfite oxidation is suitable for fermentation process scale-up studies. Cooper et al. established that the reaction proceeds at a rate independent of sulfite ion concentration over wide concentration ranges. In their work they considered the sulfite oxidation to be of zero order with respect to both sulfite and sulfate concentration. 

Sulfite Oxidation Investigated in Micro Reactors Cas/liquid reaction 27 [CL 27] Oxidation of sulfite to sulfate... 

The scheme (Fig. 15.1) thus explained the production of both sulfate and sulfur in equimolar amounts from thiosulfate oxidation. In showing adenylylsulfate as an intermediate, it also provided a feasible route for the conservation of energy from sulfite oxidation by a substrate-level phosphorylation mechanism, in which ADP sulfurylase and adenylate kinase give rise to ATP ... 

Figure. 15.2. Mechanism for the introduction of into sulfate formed during sulfite oxidation by the activities of APS reductase and ADP sulfurylase. Modified from Peck and Stulberg (1962).

Sulfite Oxidation Method The sulfite oxidation method is a classical, but still useful, technique for measuring /cgfl (or [4]. The method is based on the air oxidation of an aqueous solution of sodium sulfite (Na SOg) to sodium sulfate (Na.,SO ) with a cupric ion (Cu " ") or cobaltous ion (Co ) catalyst. With appropriate concentrations of sodium sulfite (about 1 N) or cupric ions (>10 inolH ), the value of k for the rate of oxygen absorption into sulfite solution, which can be determined by chemical analysis, is practically equal to Zr, for the physical oxygen absorption into sulfate solution in other words, the enhancement factor E, as defined by Equation 6.20, is essentially equal to unity. 

Zinc forms a wide variety of other salts, many by reaction with the adds, though some can only be obtained by fusing the oxides together. The salts include arsenates (ortho, pyro, and meta), the borate, bromate, chlorate, chlorite, various chromates, cyanide, iodate. various periodates, permanganate, phosphates (ortho, pyro, meta, various double phosphates 1. die selenate, selenites, various silicates, fluosilicate. sulfate, sulfite, and duocyanate. 

Indeed, if methanol is heated with fuming sulfuric acid, dimethyl sulfate, CH30(S02)0CH3, is obtained but other alcohols are better converted to dialkyl sulfates by oxidation of the corresponding dialkyl sulfites formed by the reaction of 1 mole of thionyl chloride (SOCl2) with 2 moles of the alcohol ... 

The sodium sulfite oxidation method (Cooper et al., 1944) is based on the oxidation of sodium sulfite to sodium sulfate in the presence of catalyst (Cu++ or Co++) as... 

High temperature thermodynamic data are available only for three sulfites calcium, potassium, and sodium. Most sulfites are fairly unstable, decomposing at relatively low temperatures. The decomposition reactions are not always exactly known, with diverse decomposition products, including sulfur, being reported. There are two major decomposition reactions (1) decomposition to the oxide and S02, and (2) oxidation-reduction (disproportionation) to the sulfate and oxide and S02, i.e.,... 

Another inorganic reaction that can be catalyzed by supported porphyrins is the air oxidation of sulfite to sulfate. Sulfite is formed upon absorption of SO2 from flue gases. For this reaction, a 2-V-methylpyridiniumyl-substituted... 

Figure 11. A CEPT-based mechanism for sulfite oxidation, (a) This view, prepared from PDB coordinates, illustrates the two sulfate ions and associated hydrogen-bonded water molecules. (b) Use of second coordination sphere water as a source of an oxygen atom for forming sulfate.

As a hard base, water prefers to coordinate to the harder acid Ba +, the softer base ammonia prefers to coordinate the softer acid Ag+ to form Ba(OH2) + and Ag(NH3)2+, respectively. Sulfates, sulfites, carbonates, phosphates, arsenates, oxides, and sulfides are virtually insoluble in ammonia. Hydroxides and amides are also very poorly soluble. 

Oxidized sulfur species occurring in natural waters (sulfate, sulfite, thiosulfate] do not interact with the platinum electrode when in the presence of H2S and the pH-Eh-E52- relations found were similar to the above relations. Thus, the unambiguous relations found between pH, Eh and E22- in aqueous solutions of hydrogen sulfide can be employed to characterize solutions and water samples where hydrogen sulfide is the only reduced sulfur species present. 

SO is found in various vertebrate liver tissues and catalyzes the two-electron oxidation of sulfite to sulfate coupled to the reduction of two molecules of oxidized Cyt c. It contains molybdopterin and b-heme cofactors in separate domains connected by a polypeptide bridge, analogous to Fcyt b. The smaller N-terminal heme domain resembles cytochrome b the C-terminal domain contains Mo(VI) and catalyzes sulfite oxidation coupled to oxo group transfer. Two one-electron intramolecular ET steps, each followed by ET to Cyt c, complete the catalytic cycle. 

During the scrubbing operation some of the sulfites are oxidized to sulfates the oxidation products appear to be continuously removed from the scrubbing liquor by similar reactions in the regenerator. 

All the oxidants discussed above [X2, H202,02, Mn02, Fe(III) minerals] react with sulfide to form polysulfides as the first sulfur oxidation product. These, in turn, are able to react further depending on conditions to form SH, thiosulfate, sulfite, and sulfate. Sulfite is typically a minor component in all sulfide oxidation reactions probably because of its high reactivity with oxidants and its reaction... 

Recently, some bacteria have been found which oxidize organic or inorganic compounds with arsenate or selenate (arsenic and selenium respiration) (Stolz and Oremland, 1999). Although many of these bacteria are heterotrophic, Desulfovibrio auripigmentum oxidizes hydrogen with arsenate (and with sulfate, sulfite, thiosulfate, and fumarate). 

The sulfite oxidation pathway other than that mentioned above occurs in some thiobacilli sulfite reacts with AMP by the catalysis of adenylylsulfate reductase (APS reductase) to form APS and then APS reacts with diphosphate by the catalysis of sulfate adenylyltransferase to produce sulfate and ATP (Lyric and Suzuki, 1970c Stille and Triiper, 1984), or APS reacts with orthophosphate by the catalysis of sulfate adenylyltransferase (ADP) and ATP is formed from resulting ADP by the catalysis of adenylate kinase (Zimmermann et al., 1999). 

The effect of sulfite to sulfate ratio (oxidation fraction on adipic acid coprecipitation. 

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